Many footwear products are manufactured with the use of a “last,” a physical element that helps provides shape for the upper member during the manufacturing process. While providing an adequate base for physical manufacture, because it must fit within a footwear upper and must be capable of being removed from an assembled upper, a last is shaped somewhat different from the upper. For example, the last must be somewhat smaller than the upper to enable it to fit inside and to be removable from the upper. Additionally, last structures typically have a significantly smaller ankle opening area and a significantly overall narrower ankle structure than the final upper structure produced thereon. Additionally, last structures typically have a steeper tongue or instep area than the final upper structure produced thereon.
Because of these differences, attempting to design an upper member structure, even using computer-aided design packages (CAD programs), can be difficult or problematic if one attempts to start the design based on the last structure. The design may look somewhat different from the final product if built on the last structure because of the last's differences in size and shape. Not starting with a desired last structure for the design, however, risks developing an upper design that cannot be produced using the desired last structure. Accordingly, improvements in computer-aided design for footwear structures would be a welcome advance in the art.